Transforming growth factor-beta1 promotes the migration and invasion of sphere-forming stem-like cell subpopulations in esophageal cancer

The critical role of circular RNAs in drug resistance in gastrointestinal cancers

Nowadays, drug resistance (DR) in gastrointestinal (GI) cancers, as the main reason for cancer-related mortality worldwide, has become a serious problem in the management of patients. Several mechanisms have been proposed for resistance to anticancer drugs, including altered transport and metabolism of drugs, mutation of drug targets, altered DNA repair system, inhibited apoptosis and autophagy, cancer stem cells, tumor heterogeneity, and epithelial-mesenchymal transition. Compelling evidence has revealed that genetic and epigenetic factors are strongly linked to DR. Non-coding RNA (ncRNA) interferences are the most crucial epigenetic alterations explored so far, and among these ncRNAs, circular RNAs (circRNAs) are the most emerging members known to have unique properties. Due to the absence of 5' and 3' ends in these novel RNAs, the two ends are covalently bonded together and are generated from pre-mRNA in a process known as back-splicing, which makes them more stable than other RNAs. As far as the unique structure and function of circRNAs is concerned, they are implicated in proliferation, migration, invasion, angiogenesis, metastasis, and DR. A clear understanding of the molecular mechanisms responsible for circRNAs-mediated DR in the GI cancers will open a new window to the management of GI cancers. Hence, in the present review, we will describe briefly the biogenesis, multiple features, and different biological functions of circRNAs. Then, we will summarize current mechanisms of DR, and finally, discuss molecular mechanisms through which circRNAs regulate DR development in esophageal cancer, pancreatic cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma.

SERPINF1 Mediates Tumor Progression and Stemness in Glioma

Serpin family F member 1 (SERPINF1) reportedly plays multiple roles in various tumors; however, its clinical significance and molecular functions in glioma have been largely understudied. In the present study, we analyzed the prognostic value of SERPINF1 in three independent glioma datasets. Next, we explored the molecular functions and transcriptional regulation of SERPINF1 at the single-cell level. Moreover, in vitro experiments were conducted to evaluate the roles of SERPINF1 in the proliferation, invasion, migration, and stemness of glioma cells. Our results showed that a higher expression of SERPINF1 correlated with a poor overall survival rate in glioma patients (hazard ratio: 4.061 in TCGA, 2.017 in CGGA, and 1.675 in GSE16011, p < 0.001). Besides, SERPINF1 knockdown could suppress the proliferation, invasion, and migration of glioma cells in vitro. In addition, SERPINF1 expression was significantly upregulated in glioma stem cells (GSCs) compared to parental glioma cells. Knocking down SERPINF1 impaired the sphere formation of GSC-A172 and GSC-LN18. Bioinformatics analysis revealed that Notch signaling activation was closely associated with high SERPINF1 expression at the single-cell level. Furthermore, STAT1, CREM, and NR2F2 may participate in the transcriptional regulation of SERPINF1 in glioma. Overall, our results suggest that SERPINF1 may be a candidate prognostic predictor and potential therapeutic target for glioma.

M2 tumor-associated macrophage mediates the maintenance of stemness to promote cisplatin resistance by secreting TGF-β1 in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a deadly gastrointestinal malignancy, and chemotherapy resistance is a key factor leading to its poor prognosis. M2 tumor-associated macrophages (M2-TAMs) may be an important cause of chemoresistance in ESCC, but its exact mechanism is still unclear.

METHODS

In order to study the role of M2-TAMs in ESCC chemoresistance, CCK-8, clone formation assay, flow cytometric apoptosis assay, qRT-PCR, western blotting, and serum-free sphere formation assays were used. In vivo animal experiments and human ESCC tissues were used to confirm the findings.

RESULTS

In vitro and in vivo animal experiments, M2-TAMs reduced the sensitivity of ESCC cells to cisplatin. Mechanistically, M2-TAMs highly secreted TGF-β1 which activated the TGFβR1-smad2/3 pathway to promote and maintain the stemness characteristic of ESCC cells, which could inhibit the sensitivity to cisplatin. Using TGFβ signaling inhibitor SB431542 or knockdown of TGFβR1 could reverse the cisplatin resistance of ESCC cells. In 92 cases of human ESCC tissues, individuals with a high density of M2-TAMs had considerably higher levels of TGF-β1. These patients also had worse prognoses and richer stemness markers.

CONCLUSION

TGF-β1 secreted from M2-TAMs promoted and maintained the stemness characteristic to induce cisplatin resistance in ESCC by activating the TGFβ1-Smad2/3 pathway.

Rapid Isolation of Gastric Adenocarcinoma Cancer Stem Cells as a Target for Autologous Dendritic Cell-Based Immunotherapy

Background

Gastric cancer (GC) is a malignancy cause associated with a high death rate in the world. Cancer stem cells (CSCs) are a rare immortal subpopulation of cells within tumors with characteristics of the ability to self-renew, initiate tumor, and differentiate into defined progenies as well as and high resistance to conventional therapies.

Objectives

Despite the use of surgery and chemotherapy for GC therapy, there are no efficient therapeutic protocols for it to date. Therefore, rapid isolation of CSCs in order to therapeutic targets, especially immunotherapy is very important.

Materials and Methods

Cancerous cell suspension isolated from patients with GC was cultured in the serum-free medium containing EGF, bFGF, LIF, and heparin under non-adherent culture conditions to generate spheres. Expression of mRNA level stemness transcription factors (OCT4, SOX2, SALL4, and Cripto-1), CD44 variable isoforms (CD44s, CD44v3, CD44v6, CD44V8-10) of spheroid-forming single cells compared with gastric normal tissue cells using real time PCR and molecules of CD44, CD54, and EpCAM as gastric CSC markers, and stemness factor Oct4 using flow cytometry, as well as tumorgenicity using subcutaneous injection of sphere-forming cells to nude mice were investigated.

Results

Few cancerous cells isolated from patients with GC were able to generate three-dimensional spheroid colonies in the serum-free medium containing EGF, bFGF, LIF, and heparin under non-adherent culture conditions, and form xenograft tumors in immunodeficient nude mice after subcutaneous injection. Spheroid-forming single cells upregulated stemness transcription factors OCT4, SOX2, SALL4, and Cripto-1 that are associated with pluripotency and self-renewal and CD44 isoforms (CD44s, CD44v3, CD44v6, CD44V8-10) compared with gastric normal tissue cells. Finally, molecules of CD44, CD54, and EpCAM as gastric CSC markers and stemness factor Oct4 were expressed in sphere-forming cells.

Conclusion

We suggested that the sphere formation and tumorigenicity assays are two procedures, leading to the rapid isolation of cancer cells with certain stem-like properties in order to target CSCs using autologous dendritic cell therapy, especially in patients with advanced disease.

Molecular mechanisms associated with chemoresistance in esophageal cancer

Esophageal cancer (EC) is one of the most incident and lethal tumors worldwide. Although surgical resection is an important approach in EC treatment, late diagnosis, metastasis and recurrence after surgery have led to the management of adjuvant and neoadjuvant therapies over the past few decades. In this scenario, 5-fluorouracil (5-FU) and cisplatin (CISP), and more recently paclitaxel (PTX) and carboplatin (CBP), have been traditionally used in EC treatment. However, chemoresistance to these agents along EC therapeutic management represents the main obstacle to successfully treat this malignancy. In this sense, despite the fact that most of chemotherapy drugs were discovered several decades ago, in many cases, including EC, they still represent the most affordable and widely employed treatment approach for these tumors. Therefore, this review summarizes the main mechanisms through which the response to the most widely chemotherapeutic agents used in EC treatment is impaired, such as drug metabolism, apoptosis resistance, cancer stem cells (CSCs), cell cycle, autophagy, energetic metabolism deregulation, tumor microenvironment and epigenetic modifications.

Regulatory role of the transforming growth factor-β signaling pathway in the drug resistance of gastrointestinal cancers

Gastrointestinal (GI) cancer, including esophageal, gastric, and colorectal cancer, is one of the most prevalent types of malignant carcinoma and the leading cause of cancer-related deaths. Despite significant advances in therapeutic strategies for GI cancers in recent decades, drug resistance with various mechanisms remains the prevailing cause of therapy failure in GI cancers. Accumulating evidence has demonstrated that the transforming growth factor (TGF)-β signaling pathway has crucial, complex roles in many cellular functions related to drug resistance. This review summarizes current knowledge regarding the role of the TGF-β signaling pathway in the resistance of GI cancers to conventional chemotherapy, targeted therapy, immunotherapy, and traditional medicine. Various processes, including epithelial-mesenchymal transition, cancer stem cell development, tumor microenvironment alteration, and microRNA biogenesis, are proposed as the main mechanisms of TGF-β-mediated drug resistance in GI cancers. Several studies have already indicated the benefit of combining antitumor drugs with agents that suppress the TGF-β signaling pathway, but this approach needs to be verified in additional clinical studies. Moreover, the identification of potential biological markers that can be used to predict the response to TGF-β signaling pathway inhibitors during anticancer treatments will have important clinical implications in the future.

The role of transforming growth factor β in upper gastrointestinal cancers: A systematic review

Esophageal and gastric malignancies are associated with poor prognosis, in part due to development of recurrences or metastases after curative treatment. The transforming growth factor β (TGF-β) pathway might play a role in the development of treatment resistance. In this systematic review, we provide an overview of preclinical studies investigating the role of TGF-β in esophageal and gastric malignancies. We systematically searched MEDLINE/PubMed and EMBASE for eligible preclinical studies describing the effect of TGF-β or TGF-β inhibition on hallmarks of cancer, such as proliferation, migration, invasion, angiogenesis and immune evasion. In total, 2107 records were screened and 45 articles were included, using mouse models and 45 different cell lines. TGF-β failed to induce apoptosis in twelve of sixteen tested cell lines. TGF-β could either decrease (five cell lines) or increase proliferation (seven cell lines) in gastric cancer cells, but had no effect in esophageal cancer cells. In all esophageal and all but two gastric cancer cell lines, TGF-β increased migratory, adhesive and invasive capacities. In vivo studies showed increased metastasis in response to TGF-β treatment. Additionally, TGF-β was shown to induce vascular endothelial growth factor production and differentiation of cancer-associated fibroblasts and regulatory T-cells. In conclusion, we found that TGF-β enhances hallmarks of cancer in most gastric and esophageal cancer cell lines, but not in all. Therefore, targeting the TGF-β pathway could be an attractive strategy in patients with gastric or esophageal cancer, but additional clinical trials are needed to define patient groups who would benefit most.

Roles of voltage‑gated potassium channels in the maintenance of pancreatic cancer stem cells

The targeting of membrane proteins that are activated in cancer stem cells (CSCs) represents one of the key recent strategies in cancer therapy. The present study analyzed ion channel expression profiles and functions in pancreatic CSCs (PCSCs). Cells strongly expressing aldehyde dehydrogenase 1 family member A1 (ALDH1A1) were isolated from the human pancreatic PK59 cell line using fluorescence-activated cell sorting, and PCSCs were identified based on tumorsphere formation. Microarray analysis was performed to investigate the gene expression profiles in PCSCs. ALDH1A1 messenger RNA levels were higher in PCSCs compared with non-PCSCs. PCSCs were resistant to 5-fluorouracil and capable of redifferentiation. The results of the microarray analysis revealed that gene expression related to ion channels, including voltage-gated potassium channels (Kv), was upregulated in PCSCs compared with non-PCSCs. 4-Aminopyridine (4-AP), a potent Kv inhibitor, exhibited greater cytotoxicity in PCSCs compared with non-PCSCs. In a xenograft model in nude mice, tumor volumes were significantly lower in mice inoculated with PK59 cells pre-treated with 4-AP compared with those in mice injected with non-treated cells. The present results identified a role of Kv in the persistence of PCSCs and suggested that the Kv inhibitor 4-AP may have potential as a therapeutic agent for pancreatic carcinoma.

TGF-β1 Receptor Inhibitor SB525334 Attenuates the Epithelial to Mesenchymal Transition of Peritoneal Mesothelial Cells via the TGF-β1 Signaling Pathway

We investigated the effect of SB525334 (TGF-β receptor type 1 (TβRI) inhibitor) on the epithelial to mesenchymal transition (EMT) signaling pathway in human peritoneal mesothelial cells (HPMCs) and a peritoneal fibrosis mouse model. In vitro experiments were performed using HPMCs. HPMCs were treated with TGF-β1 and/or SB525334. In vivo experiments were conducted with male C57/BL6 mice. The 0.1% chlorhexidine gluconate (CG) was intraperitoneally injected with or without SB52534 administration by oral gavage. Mice were euthanized after 28 days. EMT using TGF-β1-treated HPMCs included morphological changes, cell migration and invasion, EMT markers and collagen synthesis. These pathological changes were reversed by co-treatment with SB525334. CG injection was associated with an increase in peritoneal fibrosis and thickness, which functionally resulted in an increase in the glucose absorption via peritoneum. Co-treatment with SB525334 attenuated these changes. The levels of EMT protein markers and immunohistochemical staining for fibrosis showed similar trends. Immunofluorescence staining for EMT markers showed induction of transformed cells with both epithelial and mesenchymal cell markers, which decreased upon co-treatment with SB525334. SB525334 effectively attenuated the TGF-β1-induced EMT in HPMCs. Cotreatment with SB525334 improved peritoneal thickness and fibrosis and recovered peritoneal membrane function in a peritoneal fibrosis mouse model.

Advances in Drug Resistance of Esophageal Cancer: From the Perspective of Tumor Microenvironment

Drug resistance represents the major obstacle to get the maximum therapeutic benefit for patients with esophageal cancer since numerous patients are inherently or adaptively resistant to therapeutic agents. Notably, increasing evidence has demonstrated that drug resistance is closely related to the crosstalk between tumor cells and the tumor microenvironment (TME). TME is a dynamic and ever-changing complex biological network whose diverse cellular and non-cellular components influence hallmarks and fates of tumor cells from the outside, and this is responsible for the development of resistance to conventional therapeutic agents to some extent. Indeed, the formation of drug resistance in esophageal cancer should be considered as a multifactorial process involving not only cancer cells themselves but cancer stem cells, tumor-associated stromal cells, hypoxia, soluble factors, extracellular vesicles, etc. Accordingly, combination therapy targeting tumor cells and tumor-favorable microenvironment represents a promising strategy to address drug resistance and get better therapeutic responses for patients with esophageal cancer. In this review, we mainly focus our discussion on molecular mechanisms that underlie the role of TME in drug resistance in esophageal cancer. We also discuss the opportunities and challenges for therapeutically targeting tumor-favorable microenvironment, such as membrane proteins, pivotal signaling pathways, and cytokines, to attenuate drug resistance in esophageal cancer.

Regulatory T cells promote glioma cell stemness through TGF-β-NF-κB-IL6-STAT3 signaling

Glioma stem cells (GSCs) contribute to the malignant growth of glioma, but little is known about the interaction between GSCs and tumor microenvironment. Here, we found that intense infiltration of regulatory T cells (Tregs) facilitated the qualities of GSCs through TGF-β secretion that helped coordinately tumor growth. Mechanistic investigations indicated that TGF-β acted on cancer cells to induce the core cancer stem cell-related genes CD133, SOX2, NESTIN, MUSASHI1 and ALDH1A expression and spheres formation via NF-κB–IL6–STAT3 signaling pathway, resulting in the increased cancer stemness and tumorigenic potential. Furthermore, Tregs promoted glioma tumor growth, and this effect could be abrogated with blockade of IL6 receptor by tocilizumab which also demonstrated certain level of therapeutic efficacy in xenograft model. Additionally, expression levels of CD133, IL6 and TGF-β were found to serve as prognosis markers of glioma patients. Collectively, our findings reveal a new immune-associated mechanism underlying Tregs-induced GSCs. Moreover, efforts to target this network may be an effective strategy for treating glioma.

Effects of immune cells and cytokines on inflammation and immunosuppression in the tumor microenvironment

Chronic inflammation and immune responses are two core element that characterize the tumor microenvironment. A large number of immune/inflammatory cells (including tumor associated macrophages, neutrophils and myeloid derived suppressor cells) as well as cytokines (such as IL-6, IL-10, TGF-β) are present in the tumor microenvironment, which results in both a chronic inflammatory state and immunosuppression. As a consequence tumor cell migration, invasion, metastasis and anticancer drug sensitivity are modulated. On the one hand, secreted cytokines change the function of cytotoxic T lymphocytes and antigen presenting cells, thereby inhibiting tumor specific immune responses and consequently inducing a special immunosuppressive microenvironment for tumor cells. On the other hand, tumor cells change the differentiation and function of immune/inflammatory cells in the tumor microenvironment especially via the NF-κB and STAT3 signaling pathways. This may promote proliferation of tumor cells. Here we review these double edged effects of immune/inflammatory cells and cytokines on tumor cells, and explored their interactions with inflammation, hypoxia, and immune responses in the tumor microenvironment. The tumor inflammatory or immunosuppressive reactions mediated by the high activity of NF-κB or STAT3 can occur alone or simultaneously, and there is a certain connection between them. Inhibiting the NF-κB or STAT3 signaling pathway is likely to curb the growth of tumor cells, reduce the secretion of pro-inflammatory factors, and enhance the anti-tumor immune response.

Linking Cancer Stem Cell Plasticity to Therapeutic Resistance-Mechanism and Novel Therapeutic Strategies in Esophageal Cancer

Esophageal cancer (EC) is an aggressive form of cancer, including squamous cell carcinoma (ESCC) and adenocarcinoma (EAC) as two predominant histological subtypes. Accumulating evidence supports the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. In this review, we aim to collect the current evidence on CSCs in esophageal cancer, including the biomarkers/characterization strategies of CSCs, heterogeneity of CSCs, and the key signaling pathways (Wnt/β-catenin, Notch, Hedgehog, YAP, JAK/STAT3) in modulating CSCs during esophageal cancer progression. Exploring the molecular mechanisms of therapy resistance in EC highlights DNA damage response (DDR), metabolic reprogramming, epithelial mesenchymal transition (EMT), and the role of the crosstalk of CSCs and their niche in the tumor progression. According to these molecular findings, potential therapeutic implications of targeting esophageal CSCs may provide novel strategies for the clinical management of esophageal cancer.

Inhibiting of self-renewal, migration and invasion of ovarian cancer stem cells by blocking TGF-β pathway

OBJECTIVE

To investigate the effect and mechanism of SB525334 on self-renewal, migration and invasion of ovarian cancer stem cells.

METHODS

ALDHhigh-expressing cancer stem cells (CSCs) were isolated from human ovarian cancer cell line SKOV-3 by flow cytometry and treated with 2μg/mL SB525334 for 6h. The sphere forming assay was used to detect the ability of self-renewal of CSCs and the colony formation assay was used to detect the tumorigenicity in vitro. Transwell migration and invasion assay were used to detect the migration and invasion ability of CSCs. To further explore the mechanism, real-time quantitative PCR and flow cytometry were used to detect the mRNA and protein expression of TGF-β, Smad2, Smad3, phosphorylated Smad2, phosphorylated Smad3 and Smad4, respectively. Expressions of epithelial-mesenchymal transition (EMT)-related genes E-cadherin, Snail, Vimentin were also assessed.

RESULTS

The self-renewal ability, tumorigenicity in vitro, migration and invasion ability of CSCs were significantly attenuated after SB525334 treatment. The expressions of TGF-β, phosphorylated Smad2, phosphorylated Smad3, Snail, and Vimentin were decreased, while Smad4 and E-cadherin expressions were increased.

CONCLUSION

SB525334 may inhibit the self-renewal, invasion and migration of ovarian CSCs by blocking the TGF-β/Smad/EMT pathway.

Krüppel-like factor 4 regulates stemness and mesenchymal properties of colorectal cancer stem cells through the TGF-β1/Smad/snail pathway

Krüppel-like factor 4 (KLF4) was closely associated with epithelial-mesenchymal transition and stemness in colorectal cancer stem cells (CSCs)-enriched spheroid cells. Nonetheless, the underlying molecular mechanism is unclear. This study showed that KLF4 overexpression was accompanied with stemness and mesenchymal features in Lgr5⁺ CD44⁺ EpCAM⁺ colorectal CSCs. KLF4 knockdown suppressed stemness, mesenchymal features and activation of the TGF-β1 pathway, whereas enforced KLF4 overexpression activated TGF-β1, phosphorylation of Smad 2/3 and Snail expression, and restored stemness and mesenchymal phenotypes. Furthermore, TGF-β1 pathway inhibition invalidated KLF4-facilitated stemness and mesenchymal features without affecting KLF4 expression. The data from the current study are the first to demonstrate that KLF4 maintains stemness and mesenchymal properties through the TGF-β1/Smad/Snail pathway in Lgr5⁺ CD44⁺ EpCAM⁺ colorectal CSCs.

Cancer stem cells in esophageal squamous cell cancer

Cancer stem cells (CSCs) are hypothesized to govern the origin, progression, drug resistance, recurrence and metastasis of human cancer. CSCs have been identified in nearly all types of human cancer, including esophageal squamous cell cancer (ESCC). Four major methods are typically used to isolate or enrich CSCs, including: i) fluorescence-activated cell sorting or magnetic-activated cell sorting using cell-specific surface markers; ii) stem cell markers, including aldehyde dehydrogenase 1 family member A1; iii) side population cell phenotype markers; and iv) microsphere culture methods. ESCC stem cells have been identified using a number of these methods. An increasing number of stem cell signatures and pathways have been identified, which have assisted in the clarification of molecular mechanisms that regulate the stemness of ESCC stem cells. Certain viruses, such as human papillomavirus and hepatitis B virus, are also considered to be important in the formation of CSCs, and there is a crosstalk between stemness and viruses-associated genes/pathways, which may suggest a potential therapeutic strategy for the eradication of CSCs. In the present review, findings are summarized along these lines of inquiry.

13C Tracer Analysis and Metabolomics in 3D Cultured Cancer Cells

Metabolomics and ¹³C tracer analysis are state-of-the-art techniques that allow determining the concentration of metabolites and the activity of metabolic pathways, respectively. Three dimensional (3D) cultures of cancer cells constitute an enriched in vitro environment that can be used to assay anchorage-independent growth, spheroid formation, and extracellular matrix production by (cancer) cells. Here, we describe how to perform metabolomics and ¹³C tracer analysis in 3D cultures of cancer cells.

Long non-coding RNA DANCR promotes cell proliferation, migration, invasion and resistance to apoptosis in esophageal cancer

BACKGROUND

Long non-coding RNAs (lncRNAs) have important effects on the development and progression of multiple carcinomas. Our studies aimed to investigate the expression of lncRNA DANCR in esophageal squamous cell carcinoma (ESCC) tissues and paracancerous tissues, and to explore its effect on the cell biological characteristics of ESCC ECA109 cells.

METHODS

The expression of DANCR was detected by qRT-PCR in human ESCC tissues and paracancerous normal tissues in ESCC patients. Small interfering RNA (siRNA) was transfected to knock down the expression of DANCR and interference efficiency was analyzed by qRT-PCR in ECA109 cells. MTT, wound healing, Transwell, TUNEL and flow cytometry (FCM) assay was used to measure the influence of DANCR on proliferation, invasion, migration and apoptosis in ECA109 cells, respectively.

RESULTS

The expression of DANCR in ESCC tissues and ESCC cells was significantly higher compared with that in the adjacent normal tissues (P<0.05). Furthermore, cell proliferation, migration and invasion were significantly suppressed by knock-down mediated down-regulation of DANCR expression. On the contrary, cell apoptosis was promoted by silencing of DANCR.

CONCLUSIONS

According to our research, the expression of DANCR was up-regulated in human ESCC tissues, and the important role that DANCR played in ESCC cells was similar to an oncogene. Therefore, silencing of lncRNA DANCR could have potentially beneficial effects on the prognostic and therapy for ESCC in the future.

Identification of molecular targets for esophageal carcinoma diagnosis using miRNA-seq and RNA-seq data from The Cancer Genome Atlas: a study of 187 cases

Esophageal carcinoma (ESCA) is one of the most common malignancies worldwide, and its pathogenesis is complex. In this study, we identified differentially expressed miRNAs (DEMs) and genes (DEGs) of ESCA from The Cancer Genome Atlas (TCGA) database. The diagnostic values of DEMs were determined by receiver operating characteristic (ROC) analyses and validated based on data from Gene Expression Omnibus (GEO). The top five DEMs with the best diagnostic values were selected, and their potential targets were predicted by various in silico methods. These target genes were then identified among the DEGs from TCGA. Furthermore, the overlapping genes were subjected to protein-protein interaction (PPI) analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The miRNA-transcription factor (TF) regulatory relations were determined using CircuitsDB and TransmiR. Finally, the regulatory networks of miRNA-TF and miRNA-gene were constructed and analyzed. A total of 136 DEMs and 3541 DEGs were identified in ESCA. The top five DEMs with the highest area under the receiver operating characteristic curve (AUC) values were miRNA-93 (0.953), miRNA-21 (0.928), miRNA-4746 (0.915), miRNA-196a-1 (0.906) and miRNA-196a-2 (0.906). The combined AUC of these five DEMs was 0.985. The KEGG analysis with 349 overlapping genes showed that the calcium signaling pathway and the neuroactive ligand-receptor interaction were the most relevant pathways. The regulatory networks of miRNA-TF and miRNA-gene, including 38 miRNA-TF and 560 miRNA-gene pairs, were successfully established. Our findings may provide new insights into the molecular mechanisms of ESCA pathogenesis. Future research will aim to explore the role of novel miRNAs in the pathogenesis and improve the early diagnosis of ESCA.

Expression and functional regulation of stemness gene Lgr5 in esophageal squamous cell carcinoma

Cancer stem cells (CSCs) are defined as a rare subpopulation of undifferentiated cells with biological characteristics that include the capacity for self-renewal, differentiation into various lineages, and tumor initiation. To explore the mechanism of CSCs in esophageal squamous cell carcinoma (ESCC), we focused on Leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5), a target gene of the Wnt signaling pathway, which has been identified as a marker of intestinal stem cells and shown to be overexpressed in several human malignancies. Lgr5 expression was significantly correlated with lymph node metastasis, increased depth of invasion, increased tumor size, advanced differentiation, higher AJCC stage and poorer survival. Silencing of Lgr5 expression in the ESCC cell line KYSE450 by small interfering RNA (siRNA) strongly inhibited cell proliferation, migration and invasion ability, the expression of CSCs-related genes and Wnt/β-catenin signaling. In addition, Lgr5 was highly expressed in ESCC spheroid body cells, which were identified by high expression of CSCs-related genes, and high tumorigenicity in vivo. Taken together, these results demonstrate that Lgr5 activation of Wnt/β-catenin signaling is a potential mechanism to promote the progression of ESCC and ESCC stem cell renewal, and Lgr5 may be used as a molecular target for the development of treatments for ESCC.

Enhanced circulating transforming growth factor beta 1 is causally associated with an increased risk of hepatocellular carcinoma: a mendelian randomization meta-analysis

The aim of this study was to test the causal association between circulating transforming growth factor beta 1 (protein: TGF-β1 and coding gene: TGFB1) and hepatocellular carcinoma by choosing TGFB1 gene C-509T polymorphism as an instrument in a Mendelian randomization (MR) meta-analysis. Ten English articles were identified for analysis. Two authors independently assessed each article and abstracted relevant data. Odds ratio (OR) and weighted mean difference (WMD) with 95% confidence interval (CI) were synthesized under a random-effects model. Overall, the association of C-509T polymorphism with hepatocellular carcinoma was negative, but its association with circulating TGF-β1 was statistically significant, with a higher concentration observed in carriers of the -509TT genotype (WMD, 95% CI, P: 1.72, 0.67–2.78, 0.001) and -509TT/-509TC genotypes (WMD, 95% CI, P: 0.98, 0.43–1.53, < 0.001). In subgroup analysis, C-509T polymorphism was significantly associated with hepatocellular carcinoma in population-based studies under homozygous-genotype (OR, 95% CI, P: 1.74, 1.08–2.80, 0.023) and dominant (OR, 95% CI, P: 1.48, 1.01–2.17, 0.047) models. Further MR analysis indicated that per unit increase in circulating TGF-β1 was significantly associated with a 38% (95% CI: 1.03–4.65) and 49% (95% CI: 1.01–6.06) increased risk of hepatocellular carcinoma under homozygous-genotype and dominant models, respectively. Conclusively, based on a MR meta-analysis, our findings suggest that enhanced circulating TGF-β1 is causally associated with an increased risk of hepatocellular carcinoma.

Esophageal cancer stem cells are suppressed by tranilast, a TRPV2 channel inhibitor

BACKGROUND

Recent evidence suggests that the targeting of membrane proteins specifically activated in cancer stem cells (CSCs) is an important strategy for cancer therapy. The objectives of the present study were to investigate the expression and activity of ion-transport-related molecules in the CSCs of esophageal squamous cell carcinoma.

METHODS

Cells exhibiting strong aldehyde dehydrogenase 1 family member A1 (ALDH1A1) activity were isolated from TE8 cells by fluorescence-activated cell sorting, and CSCs were then generated with the sphere formation assay. The gene expression profiles of CSCs were examined by microarray analysis.

RESULTS

Among TE8 cells, ALDH1A1 messenger RNA and protein levels were higher in CSCs than in non-CSCs. The CSCs obtained were resistant to cisplatin and had the ability to redifferentiate. The results of the microarray analysis revealed that the expression of 50 genes encoding plasma membrane proteins was altered in CSCs, whereas that of several genes related to ion channels, including transient receptor potential vanilloid 2 (TRPV2), was upregulated. The TRPV2 inhibitor tranilast was more cytotoxic at a lower concentration in CSCs than in non-CSCs, and effectively decreased the number of tumorspheres. Furthermore, tranilast significantly decreased the cell population that strongly expressed ALDH1A1 among TE8 cells.

CONCLUSIONS

The results of the present study suggest that TRPV2 is involved in the maintenance of CSCs, and that its specific inhibitor, tranilast, has potential as a targeted therapeutic agent against esophageal squamous cell carcinoma.

Esophageal 3D Culture Systems as Modeling Tools in Esophageal Epithelial Pathobiology and Personalized Medicine

The stratified squamous epithelium of the esophagus shows a proliferative basal layer of keratinocytes that undergo terminal differentiation in overlying suprabasal layers. Esophageal pathologies, including eosinophilic esophagitis, gastroesophageal reflux disease, Barrett's esophagus, squamous cell carcinoma, and adenocarcinoma, cause perturbations in the esophageal epithelial proliferation-differentiation gradient. Three-dimensional (3D) culture platforms mimicking in vivo esophageal epithelial tissue architecture ex vivo have emerged as powerful experimental tools for the investigation of esophageal biology in the context of homeostasis and pathology. Herein, we describe types of 3D culture that are used to model the esophagus, including organotypic, organoid, and spheroid culture systems. We discuss the development and optimization of various esophageal 3D culture models; highlight the applications, strengths, and limitations of each method; and summarize how these models have been used to evaluate the esophagus under homeostatic conditions as well as under the duress of inflammation and precancerous/cancerous conditions. Finally, we present future perspectives regarding the use of esophageal 3D models in basic science research as well as translational studies with the potential for personalized medicine.

SOX4 contributes to TGF-β-induced epithelial-mesenchymal transition and stem cell characteristics of gastric cancer cells

SOX4 is highly expressed in gastric cancer (GC) and is associated with tumor grade, metastasis and prognosis, however the mechanism is not clear. We report herein that SOX4 was upregulated and overexpression of SOX4 was associated with increased expression of the markers of Epithelial–mesenchymal transition (EMT) and stemness in clinic patient samples. In vitro, overexpression of SOX4 promoted the invasion as showed by Transwell assay and stemness of GC cells as assessed by sphere formation assay, which was suppressed by silencing SOX4 with shRNA. Further studies showed that SOX4 up-regulated the expression of EMT transcription factors Twist1, snail1 and zeb1 and stemness transcription factors SOX2 and OCT4, and promoted the nuclear translocation of β-catenin. Moreover, we revealed that TGF-β treatment significantly up-regulated the expression of SOX4 and silencing SOX4 reversed TGF-β induced invasion and sphere formation ability of GC cells. Finally, we showed that SOX4 promoted the lung metastasis and tumor formation ability of gastric cancer cells in nude mice. Our results suggest that SOX4 is a target TGF-β signaling and mediates TGF-β-induced EMT and stem cell characteristics of GC cells, revealing a novel role of TGF-β/SOX4 axis in the regulation of malignant behavior of GC.

Network-based method for mining novel HPV infection related genes using random walk with restart algorithm

The human papillomavirus (HPV), a common virus that infects the reproductive tract, may lead to malignant changes within the infection area in certain cases and is directly associated with such cancers as cervical cancer, anal cancer, and vaginal cancer. Identification of novel HPV infection related genes can lead to a better understanding of the specific signal pathways and cellular processes related to HPV infection, providing information for the development of more efficient therapies. In this study, several novel HPV infection related genes were predicted by a computation method based on the known genes involved in HPV infection from HPVbase. This method applied the algorithm of random walk with restart (RWR) to a protein-protein interaction (PPI) network. The candidate genes were further filtered by the permutation and association tests. These steps eliminated genes occupying special positions in the PPI network and selected key genes with strong associations to known HPV infection related genes based on the interaction confidence and functional similarity obtained from published databases, such as STRING, gene ontology (GO) terms and KEGG pathways. Our study identified 104 novel HPV infection related genes, a number of which were confirmed to relate to the infection processes and complications of HPV infection, as reported in the literature. These results demonstrate the reliability of our method in identifying HPV infection related genes. This article is part of a Special Issue entitled: Accelerating Precision Medicine through Genetic and Genomic Big Data Analysis edited by Yudong Cai & Tao Huang.

CD39/CD73 upregulation on myeloid-derived suppressor cells via TGF-β-mTOR-HIF-1 signaling in patients with non-small cell lung cancer

CD39/CD73-adenosine pathway has been recently defined as an important tumor-induced immunosuppressive mechanism. We here documented a fraction of CD11b⁺CD33⁺ myeloid-derived suppressor cells (MDSCs) in peripheral blood and tumor tissues from non-small cell lung cancer (NSCLC) patients expressed surface ectonucleotidases CD39 and CD73. Tumor TGF-β stimulated CD39 and CD73 expression, thereby inhibited T cell and NK cell activity, and protected tumor cells from the cytotoxic effect of chemotherapy through ectonucleotidase activity. Mechanistically, TGF-β triggered phosphorylation of mammalian target of rapamycin, and subsequently activated hypoxia-inducible factor-1α (HIF-1α) that induced CD39/CD73 expression on MDSCs. CD39 and CD73 on MDSCs, therefore, link their immunosuppressive and chemo-protective effects to NSCLC progression, providing novel targets for chemo-immunotherapeutic intervention.

CD39/CD73 upregulation on myeloid-derived suppressor cells via TGF-β-mTOR-HIF-1 signaling in patients with non-small cell lung cancer

CD39/CD73-adenosine pathway has been recently defined as an important tumor-induced immunosuppressive mechanism. We here documented a fraction of CD11b⁺CD33⁺ myeloid-derived suppressor cells (MDSCs) in peripheral blood and tumor tissues from non-small cell lung cancer (NSCLC) patients expressed surface ectonucleotidases CD39 and CD73. Tumor TGF-β stimulated CD39 and CD73 expression, thereby inhibited T cell and NK cell activity, and protected tumor cells from the cytotoxic effect of chemotherapy through ectonucleotidase activity. Mechanistically, TGF-β triggered phosphorylation of mammalian target of rapamycin, and subsequently activated hypoxia-inducible factor-1α (HIF-1α) that induced CD39/CD73 expression on MDSCs. CD39 and CD73 on MDSCs, therefore, link their immunosuppressive and chemo-protective effects to NSCLC progression, providing novel targets for chemo-immunotherapeutic intervention.

miR-497 suppresses epithelial-mesenchymal transition and metastasis in colorectal cancer cells by targeting fos-related antigen-1

Objective

MicroRNAs have key roles in tumor metastasis. The acquisition of metastatic capability by cancer cells is associated with epithelial–mesenchymal transition (EMT). Here, we describe the role and molecular mechanism of miR-497 in colorectal cancer (CRC) cell EMT, migration, and invasion.

Methods

Quantitative real-time polymerase chain reaction and Western blot assays were performed to detect the expression levels of miR-497 and Fos-related antigen-1 (Fra-1) in the CRC cells. HCT116 and SW480 cells with miR-497 overexpression or Fra-1 low expression were constructed by lipofection. Target prediction and luciferase reporter assays were performed to investigate whether Fra-1 is one of the targets of miR-497. Western blot and Transwell assays were performed to detect the effects of miR-497 and Fra-1 on CRC cell EMT, migration and invasion.

Results

We searched the miRanda, TargetScan, and PicTar databases and found that Fra-1, a key driver of CRC metastasis, is a potential target of miR-497. Quantitative real-time polymerase chain reaction and Western blot analysis verified downregulation of miR-497 and upregulation of Fra-1 in CRC cells. Western blot and Transwell assays showed that overexpression of miR-497 suppresses CRC cell EMT, migration, and invasion. Luciferase gene reporter assay revealed that Fra-1 is a downstream target of miR-497 as miR-497 bound directly to the 3′ untranslated region of Fra-1 messenger RNA. An inverse correlation was also found between miR-497 and Fra-1 in HCT116 and SW480 cells. Furthermore, knockdown of Fra-1 recuperated the effects of miR-497 overexpression.

Conclusion

miR-497 suppresses CRC cell EMT, migration, and invasion partly by targeting Fra-1.

Renal Carcinogenesis, Tumor Heterogeneity, and Reactive Oxygen Species: Tactics Evolved

SIGNIFICANCE

The number of kidney cancers is growing 3-5% each year due to unknown etiologies. Intra- and inter-tumor mediators increase oxidative stress and drive tumor heterogeneity. Recent Advances: Technology advancement in state-of-the-art instrumentation and methodologies allows researchers to detect and characterize global landscaping modifications in genes, proteins, and pathophysiology patterns at the single-cell level.

CRITICAL ISSUES

We postulate that the sources of reactive oxygen species (ROS) and their activation within subcellular compartments will change over a timeline of tumor evolvement and contribute to tumor heterogeneity. Therefore, the complexity of intracellular changes within a tumor and ROS-induced tumor heterogeneity coupled to the advancement of detecting these events globally are limited at the level of data collection, organization, and interpretation using software algorithms and bioinformatics.

FUTURE DIRECTIONS

Integrative and collaborative research, combining the power of numbers with careful experimental design, protocol development, and data interpretation, will translate cancer biology and therapeutics to a heightened level or leave the abundant raw data as stagnant and underutilized. Antioxid. Redox Signal. 25, 685-701.

Effect of YAP1 silencing on esophageal cancer

Background

YAP1, the nuclear effector of the Hippo pathway, has become an attractive target for treatment of malignancies and is a candidate oncogene in esophageal cancer (EC). We hypothesized that knockdown of YAP1 could suppress EC and could be used for targeted therapy. However, there are few reports of the effect of YAP1 knockdown in EC.

Materials and methods

Quantitative real-time polymerase chain reaction and Western blot assays were performed to determine the expression levels of YAP1 mRNA and protein in primary EC tissue samples, EC cell lines, and controls. Immunohistochemistry was also performed to detect YAP1 protein expression in primary EC tumor and matched nontumor control tissues. YAP1-knockdown cell lines were constructed using short-hairpin RNA, and MTT, flow cytometry, and transwell chamber assays were used to analyze the effect of YAP1 knockdown on EC cell proliferation, apoptosis, and invasion. In vivo tumor formation assays were used to investigate the antitumor effect of YAP1 knockdown.

Results

We found that YAP1 mRNA and protein were upregulated in EC and that YAP1 expression correlated significantly with metastasis and tumor stage. We also found that YAP1 knockdown repressed cell proliferation and invasion and promoted apoptosis of EC cell lines. In addition, animal experiments revealed that YAP1 knockdown suppressed the growth of esophageal tumors in vivo.

Conclusion

Collectively, these data confirm our hypothesis that YAP1 knockdown suppresses EC and suggest that YAP1 knockdown could be exploited in the targeted gene therapy of EC in the future.